Dual independent phasing system to independently phase the intake and exhaust cam lobes of a concentric camshaft arrangement

Abstract

A dual independent phasing system (DIPS) phaser assembly for coaxial camshafts having two axially stacked, thin phasing subassemblies which are each conventional vane-cell type phaser assemblies is provided. These phasers are preassembled together as a unit to make one DIPS phaser assembly. The rotor of the rear phaser is attached to the outer camshaft of the coaxial cam, and the rotor of the front phaser is attached to the inner camshaft. The radial force from the timing chain or belt is transmitted to the outer camshaft via a chain ring or pulley connected to the stator of the rear phaser. In order to provide for ease of mounting, the DIPS phaser assembly (including the front and rear phasers) is attached to the outer camshaft via mounting bolts which are passed through openings in the rotor of the front phaser in order to attach the rear phaser rotor to the outer camshaft. A central mounting bolt is used to connect the front phaser rotor to the inner camshaft. A radially stacked DIPS phaser assembly is also provided which offers further reduced axial space requirements.

1. A dual independent phasing system (DIPS) phaser assembly for coaxial camshafts comprising:
 first and second phaser subassemblies, each including a rotor with outwardly directed vanes, a stator with inwardly directed projections, each of the vanes extending between a pair of the inwardly directed projections to define pressurized hydraulic fluid chambers for advancing or retarding the rotor relative to the stator, and front and rear covers defining the front and rear walls of the chambers, the rotors being adapted for connection to an inner camshaft and an outer camshaft, respectively; 
 a timing gear or pulley connected to the stator of one of the phaser subassemblies, the timing gear or pulley being arranged to transmit radial loads into the outer camshaft; 
 the first and second phaser subassemblies are preassembled together as a unit; 
 the first and second phaser assemblies are axially arranged adjacent to each other, and the stators of the first and second phaser subassemblies are connected together; and 
 a helical equalizing spring is located between the first and second phaser assemblies and is connected between the stator and the rotor of the second phaser. 
 
     
     
       2. The DIPS phaser assembly of  claim 1 , wherein the first phaser subassembly is in front and is adapted for connection to the inner camshaft, and the second phaser subassembly is rearward and is adapted for connection to the outer camshaft. 
     
     
       3. The DIPS phaser assembly of  claim 2 , wherein each of the phaser subassemblies further comprises a radially arranged locking pin for locking the rotor in a fixed, base position relative to the stator. 
     
     
       4. The DIPS phaser assembly of  claim 3 , wherein the rotor of the front phaser includes clearance openings through which mounting bolts for connection of the rotor of the second phaser subassembly to the outer camshaft pass. 
     
     
       5. The DIPS phaser assembly of  claim 3 , further comprising a central mounting bolt to connect the front phaser rotor to the inner camshaft. 
     
     
       6. A dual independent phasing system (DIPS) phaser assembly for coaxial camshafts comprising:
 first and second phaser subassemblies, each including a rotor with outwardly directed vanes, a stator with inwardly directed projections, each of the vanes extending between a pair of the inwardly directed projections to define pressurized hydraulic fluid chambers for advancing or retarding the rotor relative to the stator, and front and rear covers defining the front and rear walls of the chambers, the rotors being adapted for connection to an inner camshaft and an outer camshaft, respectively; 
 a timing gear or pulley connected to the stator of one of the phaser subassemblies, the timing gear or pulley being arranged to transmit radial loads into the outer camshaft; 
 the first and second phaser subassemblies are preassembled together as a unit, and the second phaser subassembly is located radially around the first phaser subassembly, and the vanes of the rotor for the second phaser extend outwardly from the stator of the first phaser subassembly, forming an inner stator/outer rotor ring. 
 
     
     
       7. The DIPS phaser assembly of  claim 6 , further comprising an oil passage plate located between the front cover and the inner rotor. 
     
     
       8. The DIPS phaser assembly of  claim 7 , further comprising a central hydraulic fluid distributor that provides a pressurized hydraulic fluid path to oil passages in the oil passage plate for the pressurized hydraulic fluid chambers of the second phaser. 
     
     
       9. The DIPS phaser assembly of  claim 6 , wherein the inner stator/outer rotor ring is connectable via an adaptor to the outer camshaft.